Well, I just ran across a reference in Hugill's THE BOSUN'S LOCKER, © 2006, p. 81, to "South Spain":

"Talk about the Packet Rats, and Flyting Fish Sailors, andthe West Coast Johns and other South Spainers - why this crew was the saltiest, roustiest, full-bloodiest, sea-gull scattering crowd that ever raised a 'Hooraw chorus.'"

The implication is that "South Spainers" is a general term for sailors who sailed above and below the Equator, and from one hemisphere to another, in other words world-wide.

Cheerily,
Charley Noble